Glow plugs

[73shark]

Read the manual and haven't found how low the temp. has to be before they come on before starting. Check the other morning at +13*F and and they didn't come on. Dealer doesn't know.

Not really much of a problem since don't usually drive it in the winter but would like to know if they're functional.

Anybody know?

[gaylejoe]

I don't know what you are driving but if it's a Cummings they do not have glow plugs.

[Jim Flower]

You may or may not have a problem. If the diesel is starting ok at 13 degrees f it would seem that the glow plugs are operational but the glow plug indicator light is malfunctioning. If the engine is starting hard, the plugs may not be working and the glow plug light is not working. When the glow plugs are not working, the check engine light normally comes on. Now, if the interstate is not normally equipped with a glow plug interstate light, and the thing is starting ok, don't worry, be happy. The fix for the glow plug light, or the fix for the glow plugs is ridiculously expensive. But don't worry, the dealer most likely wont have a clue how to fix any of this stuff.

[robert claus]

I believe the glowplugs in the Mercedes Sprinter will come on anytime the coolant is cold, but they stay on longer to reach the spec temp the colder it is. The little electric coil warning light comes on and stays on until the right temp is reached. When it goes out, you start the engine. The colder it is, the longer that seems to take. If you are not getting the yellow coil light, the glowplug module may be malfunctioning. If you have a Scangauge, you will get the codes (the Scangauge II is great to have-instant mpg readings, as well as other functions). If you are having glowplug issues, you'd be getting a check engine light. For Sprinter mechanical issues, a good site is
sprintervan : Sprinter Van Mercedes Freightliner Dodge

[wayneskid]

Originally Posted by 73shark

Not really much of a problem since don't usually drive it in the winter but would like to know if they're functional.

Anybody know?

If you had any sort if problem with the glow plugs or the module that controls them, you would get a CEL indication. Interesting question though. My guess is that they come on if the engine is not at operating temp and stay on longer at colder temps.

[Protagonist]

In my Interstate, the glow plug idiot light comes on every time I turn the key to the "Run" position before starting. If the temperaturew is warm enough, the light goes out again right away; if it's cold, the light stays on longer. I never turn the key to the "Start" position until the glow plug idiot light goes out.

If the glow plug idiot light never comes on, and there's no Check Engine light, then my best guess is this…
According to my 2011 Sprinter Owner's Manual, there is a "prefuse" panel inside the battery box in the driver's footwell. Fuse #1 (actually relay module #1) on this panel is "preglow relay/secondary air pump", rated 80/40 amps.

[Wazbro]

Originally Posted by Protagonist

In my Interstate, the glow plug idiot light comes on every time I turn the key to the "Run" position before starting. If the temperaturew is warm enough, the light goes out again right away; if it's cold, the light stays on longer. I never turn the key to the "Start" position until the glow plug idiot light goes out.

Same with my '91 Mercedes turn the key to run, light comes on even at 97F with warm engine (even if it goes off immediately). Stays on longer the colder the engine is.

[Mike Leary]

We fire the glow plugs for 30 seconds when the temp is below 40 degrees. We do have a manual push-button switch with an indicator light. Unless the glow plugs are activated, she'll smoke like mad.

[Protagonist]

Originally Posted by Wazbro

Same with my '91 Mercedes turn the key to run, light comes on even at 97F with warm engine (even if it goes off immediately). Stays on longer the colder the engine is.

Yep. That's why I didn't spring for the remote-start module that went with my aftermarket Viper alarm system. A remote-starter doesn't know how long to let the glow plugs do their things before starting the vehicle.

[73shark]

OK, the "Glow plug" lite comes on when key is turned to "Run" position but goes out w/ all of the rest of the lites after the test is complete. The way I read the manual, it would stay on if the glow plugs were energized and go out when they were turned off. So I'm guessing that either it has to be colder than 13*F to come on or something is wrong but doesn't set the CEL.

Protagonist: Since yours are apparently coming on, what temp. is outside when they do?

[Wazbro]

Originally Posted by 73shark

The way I read the manual, it would stay on if the glow plugs were energized and go out when they were turned off. nce yours are apparently coming on, what temp. is outside when they do?

That part sounds weird to me, might have changed with the new Mercedes though.

On my car when the engine is cold the light comes on for 5-15 seconds.
According to the service manual the glow plugs come on for 2 minutes 30 seconds, until it starts or the key is turned off.

They do NOT shut off with the light.

The light turns off when the resistance of the glow plugs gets to a certain point which indicates the glow plugs got up to an average of the minimum temperature needed for the engine to fire.

[robert claus]

It has nothing to do with outside temp, only coolant temp. They only function for starting.

[Protagonist]

Originally Posted by Wazbro

They do NOT shut off with the light.

The light turns off when the resistance of the glow plugs gets to a certain point which indicates the glow plugs got up to an average of the minimum temperature needed for the engine to fire.

I'm not the glow plug expert. What you say sounds right, and I'm certainly not going to dispute it. I will file it away for future reference in the vast empty cavern that was once my mind.

Point of the whole thing is, if everything is working as it should the glow plug idiot light comes on every time you first turn the key to the "run" position regardless of outside temperature or engine temperature, and you should not turn the key to "start" until the glow plug idiot light goes out, indicating the cylinders are warm enough, whether that's one second later or over a minute later.

I still believe that the most likely culprit for 73shark's problem is the "preglow" relay in the battery box under the driver's footwell. A malfunctioning or nonfunctioning relay would certainly explain the symptoms he reported.

[wayneskid]

I'm still not sure 73shark has a problem. Assuming your 201? model year sprinter works like mine......

• Pre-glow light comes ON when you turn the switch to the RUN position
• Pre-glow light turns OFF when the glow plugs are up to temp. The ON time is a function of engine temperature. On my 2008 MY Sprinter the light turns off quite quickly if the engine is warm.
• If there is a failure in the glow plug system the Pre-glow light will remain ON.

With all the computerization going on in this vehicle I would be absolutely stunned if you had a failure in the glow plug system and weren't notified via either a CEL or the Pre-glow light remaining ON. This vehicle has so many sensors and computer modules that it can tell me if I have heartburn.

[flygrrl]

We have a 2007 Jeep Grand Cherokee that has the same Mercedes 3L CRD diesel engine as the Sprinters. I had to have the glow plug controller relay changed the other day because the Jeep would not start at -20C, an I had a CEL.
I add diesel conditioner every time we gas up when weather is below freezing otherwise she no go! When the weather gets chilly we also plug in an hour or so before travel and keep her out of the wind (wind chill can be below-40 around here). The other thing we do sometimes in real cold weather is double glow plug, turn key to run until glow plug light goes off, turn off key, turn on to run again until glow plug light goes off, then start vehicle. Works like a charm usually, learned this on an old VW diesel from a diesel mechanic.
I agree with wayneskid and protagonist, I am not sure 73shark has a problem, if his glow plug indicator is going on and off as he describes this seems normal. It sounds to me that 73shark wants his glowplug indicator coil light to stay ON, but it shouldn't. 13 degrees Fahrenheit could cause some difficulty starting for any unconditioned diesel that isn't run a lot in the winter. IMHO

[73shark]

Thanks to all for all of the inputs. When the dealer gets a battery isolation manager in (mine appears to be bad as the relay clicks continuously any time the solar panel is charging, even when on shore power), I'll have them explain it also and see if there's a consensus.

[Skater]

Originally Posted by Protagonist

A remote-starter doesn't know how long to let the glow plugs do their things before starting the vehicle.

I believe at least some models can be programmed/wired to check that. I'll find out more tonight - we're having a remote start installed on our diesel F-250, and I was careful to mention it was a diesel when I set up the appointment.

[Wazbro]

Originally Posted by Skater

I believe at least some models can be programmed/wired to check that. I'll find out more tonight - we're having a remote start installed on our diesel F-250, and I was careful to mention it was a diesel when I set up the appointment.

Your right some have a programmable timer to wait for the glow plugs and some can be wired to the light for the glow plugs so that when the light goes out it tries to start.

[pappy19]

Originally Posted by Protagonist

Yep. That's why I didn't spring for the remote-start module that went with my aftermarket Viper alarm system. A remote-starter doesn't know how long to let the glow plugs do their things before starting the vehicle.

I had a Clifford alarm/remote start and it was programed to alow for glow plug warm up and also to allow for a 3 minute cool down; this was on my 2002 7.3 F-350. The Clifford is made by the same company as Viper so I am sure you could have had your Viper programed for glow plug warm up on a remote start.

[Skater]

Originally Posted by Wazbro

Your right some have a programmable timer to wait for the glow plugs and some can be wired to the light for the glow plugs so that when the light goes out it tries to start.

Yeah. Honestly, the guy seemed more concerned about whether the truck had a transponder in the key (and thus needed more parts) than whether it was a diesel. I should have it back Thursday...can't wait to see how it works.